Description: Temperature controller can be done by using Electronic circuit, Microprocessor or microcontroller.
Now microcontroller is advanced among all above circuits
therefore we are using Microcontroller for temperature controlling.
In this project, microcontroller 89s51 forms the processing part,
which firstly receives data from ADC. ADC receives data from temperature sensor through amplifier.
Then microcontroller 89s51 performs the comparison of current temperature
and set temperature as per the logic of program for which microcontroller has already been programmed.
The result obtained from the above operation is given through output port of 89s51
to LCD display of relevant data and generated pulses as per the logic program
which is further fed to the driver circuit to obtain the desired output of ceiling fan.

Block Diagram:

Description:
The "Temperature Controlled Fan" is designed around the micro-controller. The main blocks of the system are:
Micro-controller board:
It is a low-power, high-performance CMOS 8-bit microcomputer with 4K bytes of Flash Programmable and Erasable Read Only Memory PEROM). The device is manufactured using Atmel’s high-density nonvolatile memory technology and is compatible with the MCS-51. Instruction set and pin out. The on chip Flash allows the program memory to be reprogrammed in-system or by a conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU with Flash on a monolithic chip, it provides a highly flexible and cost effective solution so many embedded control applications.

Temperature Sensor Block:
The temperature sensed by using LM 35. The output voltage of LM 35 varies in liner proportion with the temperature. The sensitivity of LM 35 is 10 mV/0C. For 1 0C output of LM35 is 10 mV. For 10 0C output of LM35 is 100 mV.

ADC Block:
ADC means analog to digital converter. The output of signal conditioning is in the analog form. But Microprocessor requires input in digital form for this purpose we have to use ADC. In this project we are using ADC 0808. The reference voltage is +5 V. The resolution of ADC is 20 mV. Therefore for 20 mV output of ADC is (01) H. And for 100 mV output of ADC is (05) H.

Amplifier Block:
Output signal from micro-controller 89C51 is weak so we have to amplify that signal. Amplifier block amplifies the signal for driving the final control element i.e. output device. For amplification Transistor BC 547 is used.

Output Block:
In this project we are using FAN as output device. If temperature is above set point then Fan is ON so that temperature will start to decrease

Display Block:
In this project we are using 16 X 2 intelligent LCD display to display the college name, temperature set point and very important is temperature of “Temperature Controlled Fan”.

Application and Advantage:
1. This project can be used in Home.
2. This project can be used in Industry.
3. This will help in saving the energy / electicity.

Future Development:
1. We can monitor more parameters like humidity, light and at the same time control them
2. We can send this data to a remote location using mobile or internet
3. We can draw graphs of variations in these parameters using computer

Question: How much time will it take to reach project by courier?
Answer: Project PCB is ready, so it will take 2 days to complete the proejct. And then 2 to 3 days to courier the project.

Question: Which type of fan can be controlled using this project? AC or DC ?
Answer: We have used Triac to control speed of the fan. So you have to use AC fan.
But we can provide DC fan as well if you want. Relay or transistor circuit can be provided to control speed of DC fan.
Thus user can use fan operating on 12 volt (CPU fan).

Question: I want to control the Temperature using the Computer, Desktop. Can I get PC based temperature controling ?
Answer: In the current project, Temperature monitoring on PC is possible, but it does not have facility of Controlling temperature using computer.

Do you have question or any feedback about this project?Please email your questions to: info @ mtronixtech.com